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| United States Patent |
5,081,522
|
|
Hiroyuki
|
January 14, 1992
|
Dual picture video signal processsing circuit
Abstract
A dual picture video signal processisng circuit performs a subpicture
processisng after the Y/C separation when a composite video signal is
supplied. When separate Y and C signals are supplied, the circuit performs
the subpicture processing directly to the Y and C signals. By this feature
the circuit automatically performs the subpicture processing both for the
composite video signal and the separate Y and C signals for the
subpicture, and deterioration of the picture quality of the subpicture is
prevented.
| Inventors:
|
Hiroyuki; Takahori (Tokyo, JP)
|
| Assignee:
|
Pioneer Electronic Corporation (Tokyo, JP)
|
| Appl. No.:
|
523808 |
| Filed:
|
May 16, 1990 |
Foreign Application Priority Data
| Current U.S. Class: |
348/557; 348/566 |
| Intern'l Class: |
H04N 005/272 |
| Field of Search: |
358/21 R,22 PIP,83,22 C
|
References Cited
U.S. Patent Documents
| 4750039 | Jun., 1988 | Willis | 358/22.
|
| 4782391 | Nov., 1988 | McNeeley et al. | 358/22.
|
| 4802000 | Jan., 1989 | Willis | 358/31.
|
Primary Examiner: Groody; James J.
Assistant Examiner: Vu; Kim Y.
Attorney, Agent or Firm: Wegner, Cantor, Mueller & Player
Claims
What is claimed is:
1. A dual picture video signal processing circuit comprising:
first input means for receiving a composite video signal or separate Y and
C signals as signal(s) for a main picture;
second input means for receiving a composite video signal or separate Y and
C signals as signal(s) for a subpicture;
first separating means for separating said composite video signal supplied
from said first input means into Y and C signals;
second separating means for separating said composite video signal supplied
from said second input means into Y and C signals;
selecting means for selecting either of said Y and C signals supplied from
said first input means and said Y and C signals supplied from said second
input means;
subpicture signal processing means for performing a subpicture signal
processing to either of said Y and C signals supplied from said second
input means and said Y and C signals supplied from said second separating
means; and
superimposing means for superimposing said Y and C signals processed by
said subpicture signal processing means on said Y and C signals passed
through said selecting means.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a dual picture video signal processing
circuit for use in the so-called Picture-in-Picture (P-in-P) television
set capable of displaying a subpicture in a main picture.
2. Description of Background Information
In the P-in-P television sets, there are two types of signal processing
configuration, i.e., a type in which a composite video signal for the
subpicture is directly treated by a subpicture signal processing, and a
type in which the subpicture signal processing is performed to signals
obtained after the Y and C separation.
However, conventional P-in-P television sets are constructed that the
subpicture signal processing can be performed to either of the composite
video signal and the separate Y and C signals. When the subpicture signal
processing is performed to the composite video signal, it is difficult to
determine proper hue of the picture. For this reason, there has been a
problem of degradation of the picture quality of the subpicture.
OBJECTS AND SUMMARY OF THE INVENTION
An object of the present invention is therefore to provide a dual picture
video signal processing circuit by which the subpicture signal processing
is possible both for the composite video signal and the separate Y/C
signals, and without causing degradation of the picture quality of the
subpicture.
The dual picture video signal processing circuit according to the present
invention comprises first input means for receiving a composite video
signal or separate Y and C signals as signal(s) for a main picture, second
input means for receiving a composite video signal or separate Y and C
signals as signal(s) for a subpicture, first separating means for
separating the composite video signal supplied from the first separating
means into Y and C signals, second separating means for separating the
composite video signal supplied from the second input means into Y and C
signals, selecting means for selecting either of the Y and C signals
supplied from the first input means and the Y and C signals supplied from
the second input means, subpicture signal processing means for performing
a subpicture signal processing to either of the Y and C signals supplied
from the second input means and the Y and C signals supplied from the
second separating means, and superimposing means for superimposing the Y
and C signals processed by the subpicture signal processing means on the Y
and C signals passed through the selecting means.
In the dual picture video signal processing circuit according to the
present invention, a composite video signal or separate Y and C signals
are taken as signal(s) for the main picture and a composite video signal
or separate Y and C signals are taken as signal(s) for the subpicture. If
the composite video signal is supplied the subpicture signal processing is
performed to the Y and C signals obtained by the Y/C separation and if
separate Y and C signals are supplied the subpicture signal processing is
directly effected to the separate Y and C signals, and subsequently the
signals obtained through the subpicture signal processing are superimposed
on the Y and C separation signal of the composite video signal supplied as
a signal for the main picture or the separate Y and C signals.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a block diagram showing an embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The embodiment of the present invention is specifically described with
reference to the accompanying drawings.
As shown in FIG. 2, the circuit is then supplied to receive a composite
video signal or separate Y and C signals as signal(s) for a main picture.
When a composite video signal is supplied to the circuit, it is then
supplied to one of two stationary contacts of a change-over switch SWa.
When separate Y and C signals are supplied to the circuit, the Y signal is
supplied to the other stationary contact of the change-over switch SWa,
and the C signal is supplied to an M/S (Main/Sub) change-over circuit 1 as
one input signal thereof. The composite video signal or the Y signal
selected by the change-over switch SWa is supplied to an M/S change-over
circuit 2 as one input signal thereof. The circuit also receives a
composite video signal and separate Y and C signals as signal(s) for the
subpicture. If the circuit receives a composite video signal, the
composite video signal is supplied to a change-over switch SWb as an input
signal thereof. If separate Y and C signals are supplied, the Y signal is
supplied to the other stationary contacts of the change-over switch SWb,
and the C signal is supplied to the M/S change-over circuit 1 as the other
input signal thereof. The composite video signal or the Y signal selected
by the selection switch SWb is supplied to the M/S change-over circuit 2
as the other input signal thereof. The M/S change-over circuits 1 and 2
are controlled by an M/S change-over control signal supplied from a
controller 3.
If a composite video signal is supplied to the circuit as a main picture
signal, the composite video signal is supplied to a Y/C separating circuit
4 and a sync separating circuit 5 through the selection switch SWa and the
M/S change-over circuit 2. Also, the C signal is supplied to the other
input of the selector switch SWe through the M/S change-over circuit 1.
The selector switches SWd and SWe are controlled to select the Y and C
signals separated at the Y/C separating circuit 4 when the composite video
signal is supplied to the circuit, and to select the Y and C signals when
those signals are directly supplied to the circuit.
On the other hand, when a composite video signal is supplied to the circuit
as a subpicture signal, the composite video signal is supplied to the
selector switch SWc through the selector switch SWb and the M/S
change-over circuit 2. This composite video signal is also supplied to an
LPF (Low Pass Filter) 6 and a sync separating circuit 7. The LPF 6 is
configured to permit the Y signal component contained in the composite
video signal to pass therethrough and supplies it to the A/D converter 8
of the next stage. The sync signal separating circuit 7 is configured to
extract the horizontal and vertical sync signals and supplies them to the
controller 3. When the separate Y and C signals are supplied to the
circuit as subpicture signals, the Y signal is supplied to the A/D
converter 8 after passing through the selector switch SWb, the M/S
change-over circuit 2, and the LPF 6. The C signal is supplied to the
other input of the selector switch SWc through the M/S change-over circuit
1. The selector switch SWc is configured to select the composite video
signal having passed through the M/S change-over circuit 2 when it is
supplied to the circuit, and to select the C signal having passed through
the M/S change-over circuit 1 when separate Y/C signals are supplied to
the circuit. The selector switches SWa through SWe are inter-locked with
each other, and the switch positions are controlled by a manual operation
or the operation of the controller 3.
The composite video signal selected by the selector switch 7 is demodulated
into color difference signals R-Y and B-Y at a chroma demodulation circuit
9, and the demodulated signals are supplied to a time-division A/D
converter 8 at the next stage. The A/D converter 8 is configured to
convert the Y signal supplied from the LPF 6 and the color difference
signals R-Y and B-Y supplied from the chroma demodulator circuit 9 into
digital signals in a time-division fashion, and the digital signals are
stored in a memory 10. The data of color difference signals R-Y and B-Y
and the Y signal, when read-out from the memory, is supplied to D/A
converters 11 through 13 in which the data is converted to analog signals,
respectively. The control of the A/D conversion, the writing and reading
of data into and from the memory, and the D/A conversion is performed by
the controller 3. When the size of the subpicture is to be reduced to 1/3
of the main picture, the controller 3 performs control operations so that
the subpicture signal is processed as follows. In the A/D converter 8,
every third scanning line of the subpicture signal is converted to a
digital signal, and the digitized signal is written into the memory 10. At
the time of the read-out, a timing control is performed so that the
digitized signal is read-out at a rate three times faster than the writing
speed. This signal processing operations are called "subpicture signal
processing", generally.
The color difference signals R-Y, B-Y after the D/A conversion are
modulated into the C (chroma) signal at a chroma modulation circuit 14,
and the C signal produced by the modulation is supplied to a P in P switch
circuit 15. On the other hand, the Y signal after the D/A conversion is
directly supplied to a P in P switch circuit 15. The C and Y signals for
the main picture, selected by the selector switches SWe and SWd are
supplied to the P in P switch circuits 15 and 16. The P in P switch
circuits 15 and 16 are controlled by control signals supplied from the
controller 3, to superimpose the C and Y signals for the subpicture on
predetermined regions of the C and Y signals for the main picture.
The C and Y signals after the superimposition are supplied to a video
circuit (not shown), so that the subpicture image whose size is reduced by
1/3 is simultaneously displayed in a predetermined region of the main
picture.
As described above, the dual picture video signal processing circuit
according to the present invention is configured to perform the subpicture
signal processing after the Y/C separation when a composite video signal
is supplied as the subpicture signal, and perform the subpicture signal
processing directly when separate Y and C signals are supplied. Therefore,
the subpicture signal processing can be performed automatically both for
the composite video signal and the separate Y and C signals. Moreover, the
subpicture signals obtained by the subpicture signal processing are
superimposed on the main picture signals at the stage where the subpicture
signals are treated as the Y and C signals, so that the degradation of the
picture quality of the subpicture is prevented.
As described in the foregoing, the dual picture processing circuit
according to the present invention is configured that a composite video
signal or separate Y and C signals are taken as the main picture signal
and a composite video signal or separate Y and C signals are taken as the
subpicture signal. When the composite video signal is supplied as the
subpicture signal, the composite video signal is separated into Y and C
signals, and the Y and C signals are treated by the subpicture signal
processing subsequently. When the separate Y and C signals are supplied as
the subpicture signals, those signals are directly treated by the
subpicture signal processing. Then the Y and C subpicture signals are
superimposed on Y and C signals separated from the composite video signal
supplied as the main picture signal or the separate Y and C signals
supplied as the main picture signals. Therefore, the subpicture signal
processing is possible both for the composite video signal and the
separate Y and C signals, and the degradation of the picture quality of
the subpicture is prevented.
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